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Biomedical subjects

G Merati

Publications and source records attributed to G Merati.

At least 19 recordsLinked to original sources
PubMed2005

Nutritional status and dietary patterns in disabled people.

BACKGROUND AND AIM: Obesity, cardiovascular diseases, diabetes and osteoporosis are the most frequent pathologies among people with a severe reduction of physical activity. The impairment in nutritional status, consequent to quantitative and qualitative inadequacy of diet, could be one of the first steps in the development of co-morbidities in disabled subjects. In order to evaluate this hypothesis we investigated the nutritional status and the food intake in patients with physical or mental disabilities. METHODS AND RESULTS: Thirty-seven disabled subjects (24 with exclusively physical inactivity and 13 with mental retardation and physical inactivity) mean age 33.5+/-9.2 years and 25 healthy subjects (mean age 31.0+/-9.3 years) were enrolled. Anthropometric measurements, indirect calorimetry, dual-energy X-ray absorptiometry, dietary intake and biochemical parameters were collected for each subject. Forty percent of disabled were overweight and 14% were obese. Fat free mass (FFM) and bone mineral content (BMC) was lower and fat mass (FM) was higher than able-bodied control. Absolute resting energy expenditure (REE) was lower in disabled subjects, but this difference disappeared when REE was normalized to FFM. Dietary intake resulted unbalanced (16%, 31%, 50% of total daily energy intake derived from protein, lipid and carbohydrate respectively) with a distribution of dietary fatty acid quite far from the recommended ratio [3.1(SFA):4.1(MUFA):1.0(PUFA)] and an excessive consumption of simple carbohydrates (mean intake 17.5+/-4.9%). Insufficient intake of fibre, iron, calcium, potassium and zinc was also found. Finally, alterations in the cholesterol profile were evident in more than one third of the disabled subjects, whereas fasting glucose intolerance was evident in one fourth. CONCLUSION: This study shows a consistent nutritional status impairment in disabled patients resulting in an reduction of FFM and BMC, in an over-representation of FM and in a number of biochemical risk factors for cardiovascular disease. The altered nutritional status is counterparted by a widespread inadequacy of dietary patterns. This nutritional and dietary impairment occurs both in subjects with mental and physical diseases.

Absorptiometry, Photon↗
PubMed2005

Effects of short term cast wearing on respiratory and cardiac responses to submaximal and maximal exercise in adolescents with idiopathic scoliosis.

AIM: Bracing is widely used to treat adolescent scoliosis. However, bracing may also affect respiratory and cardiovascular function. In this thirteen-weeks longitudinal study we evaluated the effect of brace wearing on maximal and submaximal cardiorespiratory capacity in adolescents with moderate idiopathic scoliosis. METHODS: Eight boys and 8 girls (12-18 years) with scoliosis of the thoracic spine (Cobb angle range 32 degrees - 42 degrees in boys and 32 degrees - 60 degrees in girls) were enrolled. Respiratory basal function (forced vital capacity, FVC, and forced expired volume in 1 s, FEV(1)) and cardiorespiratory adjustments to submaximal and maximal cycle ergometer exercise (heart rate, HR, pulmonary ventilation, VE, and oxygen consumption, VO(2)) were measured a week before fitting a brace, after 1 and 12 weeks of brace wearing, and a week after brace removal. RESULTS: With respect to pretreatment values: a) after 1 week of brace wearing FVC and FEV(1) were significantly reduced in both genders; b) after 12 weeks of bracing the amount of oxygen consumed per heart beat was reduced during maximal and submaximal exercises in females only; c) ventilatory efficiency was unchanged in both genders in each condition; d) oxygen uptake during maximal exercise was decreased (by about 10-20%) in females only; e) after brace removal all variables tended to regress to pretreatment values. CONCLUSIONS: Although data are preliminary and need to be confirmed on larger samples of patients, the brace appears to limit maximal exercise performance especially in girls, where it affects the cardiopulmonary efficiency. Thus, moderate physical exercise during brace wearing is advised to counteract respiratory, cardiovascular and muscle inefficiency due to ribcage movement limitations.

Adolescent↗
PubMed2003

Body composition assessment in spinal cord injury subjects.

Total and segmental body composition (fat mass, FM; fat-free mass, FFM; bone mineral density, BMD) were evaluated in 13 sedentary spinal cord injury (SCI) subjects and in 13 able-bodied healthy males (control, C) using dual X-ray absorptiometry (DXA) and skinfold methods. In the SCI group, total FM was significantly higher (31.1+/-8.2 vs. 20.8+/-6.9%) and total FFM was significantly lower (62.2+/-8.9 vs. 73.5+/-6.4%) than in C subjects. Total BMD did not differ between the SCI and C groups (1.20+/-0.11 vs. 1.30+/-0.11 g/cm(2)). In the SCI group, segmental FM was higher in the legs and trunk, whereas BMD was lower in legs only. The skinfold method significantly underestimated FM in the SCI group. Body composition is severely modified in paralyzed segments. The predictive equations developed for healthy populations appear to be inapplicable to SCI subjects.

Absorptiometry, Photon↗
PubMed2003

Energy consumption of locomotion with orthosis versus Parastep-assisted gait: a single case study.

STUDY DESIGN: Single case study. OBJECTIVES: To evaluate the energy expenditure during ambulation with the Advanced Reciprocating Gait Orthosis (ARGO), with and without functional electrical stimulation (FES), and with the Parastep system in a single subject, in order to avoid the effect of inter-subject variability. SETTING: The Centre of Sport Medicine and Bioengineering Centre 'Don C Gnocchi' Foundation ONLUS IRCCS, Milano, Italy. METHODS: A single patient (lesion level T5-T6) was trained specifically for each walking system and was evaluated after each training period. The effects of FES on muscle conditioning, spasticity and bone density were also evaluated. The HR/VO2 relationship and the energy cost of locomotion were measured during wheelchair (WHCH) use, during locomotion with ARGO (with and without FES) and Parastep system at different speeds. RESULTS: The following was observed at the end of the whole training: (a) circumferences of both lower limbs and quadriceps forces were increased, whereas fatigue index was slightly decreased, spasticity and bone density were unchanged; (b) compared to WHCH locomotion, the slope of HR/VO2 curves with ARGO was higher (slope difference=51.1 b 1O2(-1)), with ARGO+FES was similar (slope difference=-5.3 b 1O2(-1)) and with Parastep was smaller (slope difference=-55.6 b 1O2(-1)); (c) HR increased linearly with all locomotion systems, but did not rise above 125 bpm with Parastep; (d) the cost of locomotion was higher with Parastep than with ARGO (with and without FES), tested at each velocity; (e) Parastep appears to be easier to use for the subject. CONCLUSIONS: (a) FES can improve ambulation with orthosis, but the cost of locomotion remains very high; (b) the Parastep assisted gait elicits a higher energy expenditure than other orthoses, probably due to the lower speed of locomotion and to the high isometric effort of the stimulated muscles. SPONSORSHIP: This work has been partially supported by the Italian Minister of Public Health (Ricerca Finalizzata IRCCS no ICS030.7/RF97.25).

Adaptation, Physiological↗
PubMed2002

Genetic risk factors in young adults with 'cryptogenic' ischemic cerebrovascular disease.

Mutations such as factor V Leiden G1691A (FVL), prothrombin G20210A (FIIM), methylenetetrahydrofolate reductase (MTHFR) C677T, cystathionine beta-synthase (CBS) 844ins68 and endothelial cell protein C receptor (EPCR) 4031ins23 are risk factors for thromboembolism. To assess the role of these mutations in young adults with cerebral ischemia of otherwise undetermined etiology, 93 patients younger than 50 years old with thromboembolic strokes or transient ischemic attacks were studied. One hundred and eighty-six healthy age-matched and sex-matched blood donors served as controls. The FVL mutation was detected in 15/93 patients and 13/186 controls. After adjustment for smoking, arterial hypertension, and hyperlipidemia, the association of the FVL mutation with cerebral ischemia [odds ratio (OR), 3.19; 95% confidence interval (CI), 1.38-7.39] remained significant. One of 93 patients and 6/186 controls were carriers of FIIM (OR, 0.33; 95% CI, 0.04-2.75). We detected the MTHFR TT677 genotype in 9/93 patients and 26/186 controls (OR, 0.66; 95% CI, 0.30-1.47), a CBS 844ins68 mutation in 12/93 patients and 19/186 controls (OR, 1.30; 95% CI, 0.60-2.81), and an EPCR 4031ins23 mutation in 1/93 patients and in no control individual (P = 0.33). In conclusion, in younger adults the FVL mutation is a risk factor for cerebrovascular disease. FIIM, the MTHFR TT677 genotype and the CBS 844ins68 mutation did not contribute to the risk in this group of patients. The EPCR 4031ins23 mutation is very rare, its possible role needs further investigation.

Adolescent↗
PubMed2001

Cardio-respiratory adjustments and cost of locomotion in school children during backpack walking (the Italian Backpack Study).

The use of a school backpack is one of the possible causes of back pain in children. Oxygen consumption (VO2), pulmonary ventilation, and heart rate (fc) were measured in 35 pre-pubertal subjects [17 girls and 18 boys, mean (SD) age 11.3 (0.6) years]. They took part in a four-step experiment: (1) standing for 5 min, (2) walking at 3 km.h(-1) for 7 min, (3) walking at 3 km.h(-1) for 7 min carrying a school backpack weighing 8 kg, and (4) walking at 7 km.h(-1) for 5 min with no load. The occurrence of back pain in the last 2-3 years and during the last 15 days was assessed for the subjects by means of a questionnaire. Mean (SD) standing VO2, was 215 (45) ml.min(-1) during walking at 3 km.h(-1), 503 (101) ml.min(-1) during walking without a load, and increased to 541 (98) ml.min(-1) during walking with a load (P<0.01). Carrying a backpack increased fc only minimally. The energy cost of walking at 3 km.h(-1) without the backpack was 10.0 (2.0) ml O2.m(-1), and with the backpack was 10.8 (1.9) ml O2.m(-1) (P< 0.01). The net energy cost of locomotion was 0.129 (0.032) ml.kg body mass(-1).m(-1) for the unloaded condition and slightly lower, at 0.123 (0.025) ml.kg body mass(-1).m(-1) during loaded walking (P < 0.05). Ventilation did not change significantly between unloaded and loaded conditions. When the data were assessed according to the occurrence of back pain, the fc/VO2 slope was significantly lower in children without back pain, even though the net energy cost of locomotion was similar. Overall, these data suggest that the cardiovascular effortrequired for locomotion while carrying a backpack is minimal. However, fatigability and back pain are more likely to take place in less physical performing subjects. Thus, the occurrence of back pain in schoolchildren during locomotion while carrying a backpack may improve with an improvement in their level of fitness.

Back↗
PubMed2001

A 23bp insertion in the endothelial protein C receptor (EPCR) gene impairs EPCR function.

EPCR is a type I transmembrane protein, highly expressed on the endothelium of large vessels, that binds protein C and augments its activation. In this study, a 23bp insertion in the EPCR gene was found in 4/198 survivors of myocardial infarction and 3/194 patients with deep vein thrombosis. The EPCR gene with the insertion predicts a protein that lacks part of the extracellular domain, the transmembrane domain and the cytoplasmic tail. Expression studies showed that the truncated protein is not localized on the cell surface, cannot be secreted in the culture medium, and does not bind activated protein C. Since protein C activation depends on the concentration of EPCR, patients with the EPCR insertion could have a diminished protein C activation capacity. Further clinical studies of adequate samples size are necessary to establish whether or not the EPCR insertion predisposes to the development of thrombotic events.

Adult↗
PubMed2000

Paraplegic adaptation to assisted-walking: energy expenditure during wheelchair versus orthosis use.

STUDY DESIGN: To study the energy cost of locomotion during ambulation with different orthoses (HIP Guidance Orthosis Orlau Parawalker (PW), n=4; Reciprocating Gait Orthosis (RGO), n=6; RGO + FNS, n=4). OBJECTIVES: Since high energy costs of locomotion have been proposed as a major reason for early rejection of orthotic use, our aims were (a) to evaluate the impact of functional neuromuscular stimulation (FNS) on energy expenditure during orthosis-assisted ambulation; (b) to study whether energy expenditure data can predict the poor long-term patients' compliance and (c) to assess selection criteria for the assignment of the different types of orthosis. SETTING: The study was completed at the Center of Sports Medicine and Center of Bioengineering, don C. Gnocchi Foundation, IRCCS, Milan, Italy. METHODS: The HR/VO2 relationship and the energy cost of locomotion (C) were studied in 14 patients (lesion level C7-T11) during wheelchair (WHCH) use at various speeds and during locomotion with different orthotic devices. Patients' short- and long-term compliance were assessed by questionnaires evaluating duration of and problems related to orthotic use. RESULTS: (a) In patients using RGO + FNS the slope difference of HR/VO2 curves (deltaslHR/VO2) between WHCH and orthosis was significantly lower than in other groups (-3 beats l(-1) in RGO + FNS vs 43 and 52 beats l(-1) in RGO and PW, respectively); (b) neither C, nor VO2 peak, or deltaslHR/VO2 correlated with orthosis duration of use; (c) in the RGO + FNS group, C was lower at maximal walking speed, which linearly correlated with maximal WHCH speed. CONCLUSION: (a) Electrical stimulation seems to improve locomotion, as a consequence of hemodynamic effects, but does not decrease energy expenditure, which remains high; (b) the poor long-term compliance to orthosis use cannot be predicted by the energy expenditure parameters; (c) the subjects who can reach high speeds by WHCH seem to be the most appropriate for RGO + FNS locomotion.

Adaptation, Physiological↗
PubMed2000

Swim training improves myocardial resistance to ischemia in rats.

As the relationship between training and ischemic heart disease is not yet unraveled, we test the hypothesis that, in a model free from environmental, behavioural, and neuro-hormonal factors, endurance training improves myocardial resistance to ischemia. As carbohydrate metabolism is relevant for myocardial resistance to ischemia, we also test whether hyperglycemia blunts the protective effect of training. Eight-week old rats were randomly assigned to four groups (n = 6-8): sedentary or trained (3-week swim program, up to 2 h/day), and normal or high-carbohydrate diet (50 g/l sucrose in drinking water). Excised hearts were perfused isovolumically (flow = 15 ml/min) with Krebs-Henseleit (2 mM free Ca++, 11 mM glucose, pH 7.38 +/- 0.02, PO2 = 670 +/- 6 mmHg, PCO2 = 43 +/- 1 mmHg, mean +/- SE), exposed to 60 min low-flow (1.5 ml/min) ischemia, and then reperfused for 30 min (15 ml/min). In normally fed rats training increased the stroke volume index (97.5 +/- 13.0 vs. 72.6 +/- 6.2 microl, P = 0.05), depressed diastolic contracture (+2.3 +/- 2.0 vs. +24.2 +/- 6.7 mmHg, P = 0.02), improved the recovery of developed pressure x heart rate (33.8 +/- 2.3 vs. 24.1 +/- 3.3 mmHg/min/1000, P = 0.05), and decreased arrhythmias (P = 0.05). In high-carbohydrate-fed rats training induced myocardial hypertrophy (1.95 +/- 0.08 vs. 1.67 +/- 0.03 g, P = 0.02) and decreased arrhythmias but did not affect stroke volume, developed pressure x heart rate, and diastolic contracture. Thus endurance training improves myocardial resistance to ischemia but a high-carbohydrate diet partially blunts this protection. The occurrence of an inducible alteration able to modulate myocardial tolerance to ischemia may give clues to extend our knowledge of ischemic preconditioning.

Animals↗
PubMed1999

Atenolol depresses post-ischaemic recovery in the isolated rat heart.

Metabolic events during ischaemia are probably important in determining post-ischaemic myocardial recovery. The aim of this study was to assess the effects of the beta-blocker atenolol and the high energy demand in an ischaemia-reperfusion model free of neurohormonal and vascular factors. We exposed Langendorff-perfused isolated rat hearts to low-flow ischaemia (30 min) and reflow (20 min). Three groups of hearts were used: control hearts (n =11), hearts that were perfused with 2.5 micrograms l-1atenolol (n =9), and hearts electrically paced during ischaemia to distinguish the effect of heart rate from that of the drug (n =9). The hearts were freeze-clamped at the end of reflow to determine high-energy phosphates and their metabolites. During ischaemia, the pressure-rate product was 2.3+/-0.2, 5.2+/-1.1, and 3.3+/-0.3 mmHg 10(3)min in the control, atenolol and paced hearts, respectively. In addition, the ATP turnover rate, calculated from venous (lactate), oxygen uptake and flow, was higher in atenolol (11.2+/-1.7 micromol min-1) and paced (8.1+/-0.8 micromol min-1) hearts than in control (6.2+/-0.8 micromol min-1). At the end of reflow, the pressurexrate product recovered 75.1+/-6.4% of baseline in control vs 54.1+/-9.1 and 48.8+/-4.4% in atenolol and paced hearts (P<0.05). In addition, the tissue content of ATP was higher in the control hearts (15.8+/-1. 0 micromol g(dw)(-1)) than in atenolol (10.5+/-2.6 micromol g(dw)(-1)) and paced (10.9+/-1.3 micromol g(dw)(-1)) hearts. Thus, by suppressing the protective effects of down-regulation, both atenolol and pacing apparently depress myocardial recovery in this model.

Adenine Nucleotides↗
PubMed1999

Elevated serum progesterone on the day of HCG administration in IVF is associated with a higher pregnancy rate in polycystic ovary syndrome.

Our study compared 84 patients with polycystic ovary syndrome (PCOS) with 84 control patients who had normal ovaries and who were matched for the main determinants of success in in-vitro fertilization (IVF) and embryo transfer. Serum concentrations of oestradiol and progesterone on the day of human chorionic gonadotrophin (HCG) injection were significantly higher in PCOS than in normal patients (oestradiol 2016 +/- 1.8 pg/ml versus 1456 +/- 40.9 pg/ml, P < 0.01; progesterone 1.6 +/- 0.1 ng/ml versus 1.2 +/- 0.1 ng/ml, P = 0.03). Furthermore despite oocytes from PCOS patients having a reduced fertilization rate compared with normal patients (61.8 +/- 4.1% versus 73.5 +/- 4.3%, P = 0.03), the differences in pregnancy rate (22.6 versus 19%) and miscarriage (31.5 versus 18.7%) were not statistically significant. In PCOS patients, a critical breakpoint was identified at serum progesterone concentrations of 1.2 ng/ml on the day of HCG injection. The PCOS patients with progesterone > or = 1.2 ng/ml showed a higher pregnancy and miscarriage rate than PCOS patients with progesterone < 1.2 ng/ml (26.6 versus 17.9%, P < 0.01; and 41.7% versus 14.3%, P < 0.01 respectively). These findings suggest that premature progesterone production does not have an adverse effect on pregnancy rate in PCOS, but on the contrary, may be a predictor for success in IVF/embryo transfer.

Adult↗
PubMed1998

Effects of trimetazidine on metabolic and functional recovery of postischemic rat hearts.

The objective of this study was to test the hypothesis that the beneficial effect of trimetazidine during reflow of ischemic hearts is mediated by energy sparing and ATP pool preservation during ischemia. Isolated rat hearts (controls and rats treated with 10(-6) M trimetazidine, n = 17 per group) underwent the following protocol: baseline perfusion at normal coronary flow (20 minutes), low-flow ischemia at 10% flow (60 minutes), and reflow (20 minutes). We measured contractile function, O2 uptake, lactate release, venous pH and PCO2, and the tissue content of high-energy phosphates and their metabolites. During baseline, trimetazidine induced higher venous pH and lower PCO2 without influencing performance and metabolism. During low-flow ischemia, trimetazidine reduced myocardial performance (P = 0.04) and ATP turnover (P = 0.02). During reflow, trimetazidine improved performance (91 +/- 6% versus. 55 +/- 6% of baseline), prevented the development of diastolic contracture and coronary resistance, and reduced myocardial depletion of adenine nucleotides and purines. ATP turnover during low-flow ischemia was inversely related to recovery of the rate-pressure product (P = 0.002), end-diastolic pressure (P = 0.007), and perfusion pressure (P = 0.05). We conclude that trimetazidine-induced protection of ischemic-reperfused hearts is also mediated by energy sparing during ischemia, which presumably preserves the ATP pool during reflow.

Animals↗
PubMed1997

Gene polymorphisms predicting high plasma levels of coagulation and fibrinolysis proteins. A study in centenarians.

Gene polymorphisms associated with the plasma levels of fibrinogen, factor VII, and plasminogen activator inhibitor 1 (PAI-1)-hemostasis proteins that help to predict the risk of atherothrombotic disease-were compared in 124 healthy individuals > or = 100 years old and 130 young, healthy individuals to identify genetic influences on extreme longevity. We investigated the restriction fragment length polymorphism G/A-455 located in the promoter of the beta-fibrinogen gene, the guanine insertion/deletion polymorphism 4G/5G in the promoter of the PAI-1 gene, and the R353Q substitution polymorphism in exon 8 of the factor VII gene. Alleles and genotypes associated with elevated plasma levels of fibrinogen and factor VII were found with similar frequencies in centenarians and in the comparison group. However, in centenarians there was a significantly higher frequency of the 4G allele and of the homozygous 4G4G genotype associated with high PAI-1 levels. Since high PAI-1 is considered a predictor of recurrent myocardial infarction in young men, it is intriguing that the corresponding genetic marker is more frequent in centenarians who have escaped major age-related atherothrombotic disease and reached the extreme limits of human life. Homozygosity for the 4G allele, despite its association with impaired fibrinolysis, is compatible with successful aging.

Aged↗
PubMed1996

Dynamics of myocardial adaptation to low-flow ischemia and hypoxemia.

We investigated whether one or more factors control performance in O2-limited hearts. For this purpose, we measured the dynamics of myocardial adaptation to reduced O2 supply with a specially designed setup, analyzing early changes after reduction in either flow of the perfusion medium or its PO2. For 10 min, 38 isolated rat hearts underwent low-flow ischemia or hypoxemia, matched for O2 supply. Early during ischemia, developed pressure declined at a rate of 311 +/- 25 mmHg/s; lactate release increased and then leveled off to 3.4 +/- 0.7 mumol/min within 2 min. During hypoxemia, pressure dropped initially, as observed during ischemia. However, it then increased before slowly decreasing. Lactate release during hypoxemia peaked at 13.0 +/- 2.3 mumol/min after 2 min, leveling off to 3.5 +/- 1.3 mumol/min. Glycogen decreased by 52 and 81% in ischemic and hypoxemic hearts, respectively (P < 0.05). Reexposure to ischemia or hypoxemia induced comparable changes in both groups. We conclude that, at the beginning of ischemia, a single factor does limit myocardial performance. This variable, which remains undisturbed for 10 min, is presumably O2 availability. In contrast, approximately 20 s after induction of hypoxemia, glycolytic ATP production can partially override low O2 availability by providing most of the energy needed. During repeated restriction of O2 supply, O2 availability alone limits performance during both ischemia and hypoxemia.

Adaptation, Physiological↗
PubMed1996

Factor V gene mutation is a risk factor for cerebral venous thrombosis.

To evaluate the association between coagulation defects and cerebral venous thrombosis, a case-control study was conducted in 25 patients who had no autoimmune, neoplastic or infections disease and 75 healthy individuals. There were no patients with deficiency of protein C or protein S. Four had resistance to activated protein C (APC) and one had APC resistance associated with antithrombin deficiency. APC resistance was investigated by DNA analysis, and diagnosed by the presence of a point mutation in the factor V gene, which predicts replacement of Arg506 with Gln at one of the two APC cleavage sites in activated factor V. The prevalence of APC resistance was 20% in patients and 2.7% in controls. This difference was statistically significant (p = 0.01) and the odds ratio was 9.1. A circumstantial factor predisposing to cerebral venous thrombosis (such as oral contraceptive intake, pregnancy, puerperium, trauma or prolonged immobilization) was reported in 72% of cases. In conclusion, APC resistance is the most frequent coagulation abnormality associated with cerebral venous thrombosis.

Adult↗